Mechanisms for a remote response to Asian anthropogenic aerosol in boreal winter
Mechanisms for a remote response to Asian anthropogenic aerosol in boreal winter
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DOI：
10.5194/acp-19-9081-2019
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发表时间：
2019-07
影响因子：
6.3
通讯作者：
L. Wilcox;N. Dunstone;A. Lewinschal;M. Bollasina;A. Ekman;E. Highwood
中科院分区：
文献类型：
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作者：
L. Wilcox;N. Dunstone;A. Lewinschal;M. Bollasina;A. Ekman;E. Highwood
摘要。自1980年以来，亚洲人为气溶胶及其前体的排放量迅速增加，自工业化前时代以来的增加量有一半发生在这一时期。利用HadGEM3-GC2耦合模式设计了瞬态实验，以分离亚洲人为气溶胶对北半球冬季全球气候的影响。研究发现，这种增加导致了局地环流的变化，而局地环流的变化又导致了中国降水的减少，同时近海季风流的增强。中国上空没有出现大的温度变化。在印度，气温下降，降水增加，反应正好相反。局地环流变化的主要特征是海洋大陆上空低层辐合、上升和降水的增加，这构成了热带太平洋La Niña-like响应的一部分。HadGEM3-GC2还可以模拟明显的远场响应。北太平洋经向温度梯度减小导致太平洋-北美正环流型，并伴随北太平洋和北美上空的温度异常。欧洲东北部的反常东北气流驱动冷空气平流进入中欧和西欧，导致该地区降温。北大西洋上空的异常反气旋环流导致西欧上空干燥。使用稳态原始方程模型LUMA，我们证明了这些远场中纬度响应主要是由在中国产生的罗斯比波引起的，而不是在赤道太平洋。
Abstract. Asian emissions of anthropogenic aerosols and their precursors have increased rapidly since 1980, with half of the increase since the pre-industrial era occurring in this period. Transient experiments with the HadGEM3-GC2 coupled model were designed to isolate the impact of Asian anthropogenic aerosols on global climate in boreal winter. It is found that this increase has resulted in local circulation changes, which in turn have driven decreases in precipitation over China, alongside an intensification of the offshore monsoon flow. No large temperature changes are seen over China. Over India, the opposite response is found, with decreasing temperatures and increasing precipitation. The dominant feature of the local circulation changes is an increase in low-level convergence, ascent, and precipitation over the Maritime Continent, which forms part of a tropical Pacific-wide La Niña-like response. HadGEM3-GC2 also simulates pronounced far-field responses. A decreased meridional temperature gradient in the North Pacific leads to a positive Pacific–North American circulation pattern, with associated temperature anomalies over the North Pacific and North America. Anomalous northeasterly flow over northeast Europe drives advection of cold air into central and western Europe, causing cooling in this region. An anomalous anticyclonic circulation over the North Atlantic causes drying over western Europe. Using a steady-state primitive equation model, LUMA, we demonstrate that these far-field midlatitude responses arise primarily as a result of Rossby waves generated over China, rather than in the equatorial Pacific.